[Biopreservation of fish offal and poultry waste for fur animals: fermentation and biological quality [including 3 papers, review, spoilage]]

Fur animal feed is composed of waste products from the fish industry and from slaughterhouses. Unpreserved waste products provide a favourable substrate for growth of spoilage bacteria. Spoilage caused by bacteria is characterized by acute intoxication and accumulation of toxic decomposition products of protein and amino acids mainly biogenic amines. In fermented and putrefied feed high levels of biogenic amines are usually found. The present thesis deals with the use of lactic acid bacteria for biopreservation of fish offal and poultry waste and the use of free amino acids and biogenic amines to estimate feed quality. A literature review on spoilage of animal by-products biopreservation and analysis of biogenic amines in relation to feed quality is described. In experimental work lactic acid fermentation of herring offal with Lactobacillus plantarum was evaluated at substrate concentration (2, 5 and 10% dextrose) bacterial inoculation (10** (7), 10** (8) and 10** (9) cfu/g) and different initial pH (6.8, 6.5, and 6.0). The most ideal fermentation was achieved with 10** (8) cfu/g and 5% dextrose. The fermentation process was described by lactic acid production and pH decrease. Redox potential was used as an indirect parameter of the spoilage process. Four different lactic acid bacteria cultures (10** (8) cfu/g, 5% dextrose at 25 deg C.) were evaluated for biopreservation of herring offal and chicken waste. Successful fermentation monitored by high lactic acid production low and stable pH and redox potential was obtained by inoculation with Pelzyme, and Lactobacillus plantarum/Pediococcus acidilactici. Biogenic amines are of great interest in relation to feed quality and animal health. Measurements of both free amino acids and accumulation of the corresponding biogenic amines was shown to provide a useful tool for estimating biological quality of fermented fish offal and chicken/poultry waste. A new way of presenting biological quality quality index QI was introduced. QI is based on calculation of the relation between some important amino acids and their corresponding biogenic amines. Simultaneous analysis of alanine content increases the informative value of QI. Group separation followed by HPLC analyses was a simple and cheap technique to measure free amino acids and biogenic amines in biological silage. Absolute concentrations ought to be given in micromol/g material or dry matter